Sedimentation basin cleaning apparatus



Oct. 30, 1956 a. E. EASTERDAY ,768,7 9

SEDIMENTATION BASIN CLEANING APPARATUS Filed Dec. 14, 1953 5 Sheets-Sheet l y U N 1777'02/1/57-9 Oct. 30, 1956 E. E. EASTERDAY 2,768,749

SEDIMENTATION BASIN CLEANING APPARATUS 5 Sheets-Sheet 2 Filed Dec. 14, 1953 /A/ vslvme fun/v E 595M217;

Oct. 30, 1956 E. E

. EASTERDAY SEDIMEINTATION BASIN CLEANING APPARATUS Filed Dec. 14, 1955 5.. Sheets-Sheet 3 Oct. 30, 1956 E. E. EASTERDAY 2,7

SEDIMENTATION BASIN CLEANING APPARATUS Filed Dec. 14, 1 953 5 Sheets-Sheet 4 1 my mnezmr ZYMMW Oct. 30, 1956 E. E. EASTERDAY 2,768,749

SEDIMEINTATION BASIN CLEANING APPARATUS I? W t/V57 2,7 8,749 SEDIMENTATION BASIN CLEANING Q I APPARATUS h Elton E. Easterday, St. Louis Moi. I Application December 14, 1953', Serial o. 393,029 sciaims. (Cl. 210-55 This invention relates to improvements in apparatus for sediment jor sludge removal from sedimentation basins of--.-the types provided for water treatment plants, sewage, industrial waste treatment, mining sedimentation and the like.

This invention is objectively directed toward obtaining more efficient use of existing installations by keeping the sedimentationbasins at or close to the designed capacity without prohibitive expense, thereby restoring the overall efficiency to a level in keeping with the design or rated efficiency.

The usual installation may have one or more primary sedimentation basins and one or more secondary basins connected in series or parallel flow relation so that certain basins can be shut off for cleaning without taking the entire installation out of service. If the primary basins, aswell as the secondary basins, can be effectively cleaned without being taken out of service the overall efficiency can be kept at or near the design figure, therefore the present invention has as one of its objects the provision of apparatus which can effectively be used for removal of sediment without requiring shutdown.

Another object is to provide basin cleaning apparatus with automatic control means for insuring safe operation of the cleaning apparatus by limiting the load placed on the; operating components thereof, especially upon the propelling means. A further object is to provide improved cleaning apparatus whichwill be automatically operated in reverse directions throughout the full length or over the full area of sedimentation basins to remove sediment, whether it be a heavy or relatively light deposit.

Still another object is to provide improved basin cleaning apparatus which may be adapted for use in rectangular or circular basins'and which may be adapted to direct the sediment toward one or a plurality of sediment discharges.

- The improved apparatus consists in theprovision of reciprocating or oscillating sediment removing means operated by propelling cablesor chains from a common power operated unit, in the provision of automatically operating control and safety means for sensing excessive loads and for effecting the reciprocating or oscillating movement in short strokes for heavy'deposits or in full length strokes for light deposits, and in the provision of automatically operating scraper elements on the sediment removing means for relieving the build-up of excessive loads. Y

The invention furtherconsists in control-means for the propelling cables and sediment cleaning means, such control including cable slack take-up and yieldable load weighing devices for preventing cable entanglement and for safe guarding the cable against strains exceeding a predetermined safe value and for automatically reversing the operation of the apparatus so that under exceptional load strain conditions the usual long periods of reciprocation or oscillation of the cleaning means may be altered to produce short periods of relatively rapid reversals of United States Patent 2,768,749 Patented Oct. 30, 1 956 the applied power for propelling the cleaning means. In conjunction with the control means of the general character indicated, the invention consists in the provision of simple structures for the cleaning means movably supported on the floor of the basin so that the same may when encountering heavy sediment deposits assume elevated positions to aid in keeping the loads within safe values.

Other objects will appear from the following description of certain preferred embodiments of the present apparatus, but no limitation is to be inferred therefrom.

In the drawing:

Fig. 1 is a diagrammatic plan view of a sedimentation basin of rectangular shape showing the improved cleaning apparatus therefor;

Fig. 2 is a longitudinal sectional elevation of the basin taken at line 22 in Fig. 1 and showing the apparatus in greater detail;

Fig. 3 is a transverse sectional elevation of the basin taken at line 33 in Fig. 1;

Fig. 4 is a diagrammatic plan view of a circular sedimentation basin with the improved apparatus adapted therefor;

Fig. 5 is a sectional elevational view of the circular basin as seen at line 55 in Fig. 4;

Fig. 6 is a digrammatic plan view of a rectangular basin having central sediment disposal provisions for which the present apparatus is adapted;

Fig. 7 is a sectional elevational view of the control means shown in Figs. 1 and 2, this view being taken at line 77 in Fig. 1; and

Fig. 8 is an electrical circuit for the apparatus of Fig. 1, but which may be also adapted for the apparatus of Figs. 4 and 6.

In Figs. 1, 2 and 3, the sedimentation basin indicated at 10 is constructed with a floor 11, opposite end walls 12'and 13, and opposite side walls 14 and 15. The basin floor 11 is generally level and horizontal throughout, except for sediment collecting gutters 16 and 17 across its opposite ends, the gutters being connected with valve controlled discharge conduits of any suitable construction, such as that shown at 18 in Fig. 3. Inlet and outlet provisions for basin 10 are not shown as the same may be constructed in accordance with prevailing practice, and such means are not necessary to an understanding of the present invention.

The basin sediment removing means consists in an open work frame or carriage 20 having a plurality of pairs of rollers or Wheels 21 spaced along its length to support the frame in rolling contact with the basin floor 11. Each end of the frame 20 is provided with guide rollers 22 arranged in pairs to engage the walls 14 and 15. A braced superstructure 23 extends along each longitudinal side of the frame 20, and groups of scraper blade elements 24 and 25 are pivoted near the upper margins of the superstructure 23 and extend in hanging relation to near the basin floor 11 with just sufficient clearance at the floor to prevent contact therewith. In the example shown, each group has three elements. In Fig. 2, the right hand group of blade elements 24 is shown in full line in working position against the frame 20 and the left hand group of blade elements 25 is shown in full line in an open or trailing angular position relative to the frame 20 as would occur due to the flow of fluid over and around the frame during movement thereof to the right in the direction of the arrow A. The dot-ted line positions of blade elements 24 in Fig. 2 illustrate the positions assumed for reversed movement of frame 20. Obviously, frame 20 may be constructed of suitable structural members to form a rigid member of sufficient weight to tend to hold itself in rolling contact on the basin floor 11 for effective pushing action on sediment collecting in front of the closed blade elements. As sediment accumulates in front'of the closed blades, it may rise and flow over the top to pass out through the open trailing blades, or the frame may lift and ride over the same. Thus, several passes back and forth over the basin floor 11 are usually necessary to effect maximum cleaning action.

''The speed of movementof the frame 20 may also be regulated to avoid stirring up the sediment and to avoid exceeding the safe load on the propelling cables or chains.

The frame '20 is cable or chain propelled by means now to be described. At a drum station adjacent basin 10, a motor 27 is connected to a speed reducer unit 28 by belt 29, and the output shaft 30 from the unit 28 is supported in bearing stands 31, a suitable shait coupling 32 being disposed at the unit 28. The shafit 34 carries cable drums 33, 34, 35 and 36, all of which rotate together at the same speed. A control station adjacent the drums is provided with a plurality of control units 37, 38, 39 and 40, all of similar construction and performing similar control functions to be described later. The control station may be located over a pit 41 near basin '10, as shown in Figs. 1 and 2, or the same may be located over one end of the basin to utilize the basin depth for means to be described. Since the views are somewhat diagrammatic, the following description will omit details of structure deemed unnecessary to a full and complete understanding of the invention.

Drum 33 carries a cable 42 which leads through control unit 37 to a cornering pulley 43 and about a second cornering pulley 44 at the basin side wall 15, thence along the basin side 15 to a distant cornering pulley 45 set on a horizontal axis, thence downwardly in the basin along end wall 13 to a similar cornering pulley 46, and then along the basin floor 11 to a point of connection at 47 with the frame 20. Drum 36 carries a cable 49 which leads through control unit 40 and extends to a distant cornering pulley 50 at end wall 13, thence downwardly in the basin to a similar cornering pulley 51, and thence along the basin floor 11 to a point of connection at 52 with irame 20. The drum 34 carries a cable 53 leading through the control unit 38 to a cornering pulley 54-, thence across the basin end wall 12 to a cornering pulley 55 and downwardly in the basin to a cornering pulley 56, and thence to a point of connection 57 with frame 20. In a similar manner, drum 35 carries a cable 68 leading through the control unit 39 to a cornering pulley 61 and downwardly in the basin about a cornering pulley 62 and to a point of connection 63 with frame 20.

Since all of the cable drums rotate together, the drums 33 and 36 have their cables 42 and 49 respectively connected to wind or unwind in the same direction, and drums 34 and 35 have their respective cables 53 and connected to wind or unwind in the same direction, but just opposite to the cables on drums 33 and 36. Thus the drums for cables 42 and 49 alternate with the drums for cables 53 and 60 in winding up or paying out cable length for moving the frame 20 in opposite directions. Assuming that frame 20 is moving in the direction of arrow A, cables 42 and 49 are under pulling tension and are being taken onto drums 33 and 36 respectively. Cables 53 and 60 are now trailing and will be paid out from the respective drums 34 and 35} In this manner frame 20 can be reciprocated back and forth over the basin floor 11 to move the sediment alternately toward the respective collecting gutters 17 and 16.

Each gutter is provided with a clean out drag cable, a description of one being exemplary of each thereof. In Figs. 1 and 3, the drag cable 65 is provided with a plurality of space flights 66 which move through the bottom zone of the gutter 17 and propel the sediment delivered thereto by frame 20 toward the outlet 18 in the direction of arrow B. This cable is driven by pulley 67 from any convenient source of motive power 68 and extends about spaced cornering pulleys 69 and 70 adjacent the floor 11 of the basin at side walls 14 and 15. Opposite gutter 16 is similarly provided with a cleanout drag cable as shown in Fig. 1.

The upper corners of the basin 10 may be provided with suitable platforms or overhanging shelves to carry the pulleys for the frame towing cables as well as the drag chain power pulleys. These structures are shown as overhanging shelves, but are not specifically designated, as any convenient structure may beused.

Referring now to Figs. 1, 2 and 7, the control units 37 to 40, each being similar, will now be described in more detail in connection with the provision of pit 41 separate from the basin '10. Pit 41 is provided with a covering platform 72 having slot like apertures 73 therein. Over each such aperture 73 is placed a frame 74 having four vertical legs 75 and a head plate 76. A guideway 77 consisting of suitable angle elements 78 is placed within the frame 74 in depending relation from head plate 76. A spring 79 is placed within the guideway 77 and abuts the head plate 76. Spring 79 is held in unstressed position by a bumper plate 80 attached to a slide rod 81 extending through head plate 76. A cross pin 81a retains the rod 81 and plate 80 against dropping downwardly. Near the slide rod 81 and on top of head plate 76 is a fixed support 82 for a stop switch 83 and a reversing control switch 84 spaced below switch 83. A trip arm 85 is carried by the slide rod 81 in position to strike the switch 84 upon upward movement of the rod 81.

The frame 74 is provided with cable pulleys 86 (Fig. 2) carried on horizontal shafts 87 extending between adjacent legs 75. Pulleys '86 are in alignment so that, for example, the cable 42 from drum 33 may be passed over each thereof leaving a span of the cable free therebetween and in alignment with the lower curved opening of the vertical guideway 77. The free span of cable 42 between pulleys 86 is utilized to support a slack take up device comprising a pendent drop weight 88 affixed to the lower end portion of a hanger 89. The upper end portion of hanger 89 carries a pulley 90 which rides upon the cable 42 between pulleys 86. Hanger 89 has its upper end provided with a striker plate 91 in alignment with the guideway 77. The striker plate 91 is located above pulley 90 a suitable distance so that it may strike the bumper 80 and compress spring 79 at certain times in the operation of the unit. Since all of the control units 37, 38, 39 and 40 are constructed in like manner it has been deemed suflicient to designate the parts of each thereof by similar reference numerals in accordance with the above description. The pit 41 is adapted to receive the drop weights 88 and hangers 89 during operation of these control units.

Since the cable drums 33 and 36 reel in and pay out cables 42 and 49 at different rates, depending on the diameter attained by such cables at any given time, from the rates at which cables 53 and 60 are payed out andreeled in, it is necessary to take up the slack in the trailing set of cables being payed out during the time the pulling set of cables are being reeled in. The weights 88 perform this function and prevent cable piling up at the drums. In other Words, for long runs two of the drums may contain several layers of cable when the frame 20 reaches one end of the basin 10; therefore, when the frame 20 is reversed the empty drums begin winding in cable and the full drums concurrently pay out cable faster than the empty drums can reel in cable due to the difference in effective drum diameter.

In the example of Fig.1, drums 33 and 36 are empty and are reeling in cables 42 and 49, while drums 34 and 35 are filled and pay out cables 53 and 60. Under these conditions it happens that the drop weights 88 for control units 37 and '40 elevate and the drop weights 88 for confully hereinafter.

the time when the drums 34 and 35 have a larger diameter of cable than drums 33 and 36 and, as the diameter changes during the latter portion of the unwinding action, these drop weights will rise until they are again at about the same elevation with the drop weights for control units 37 and 40. Since the drop weights 88 for the pulling set of drums 33 and 36 are held up due to tension in the cable span between pulleys 36 for control units 37 and 40, the hanger striker plates 91 will bear upwardly upon bumpers S0 and compress the springs 79 to the extent dictated by the cable tension. The springs 79 thus act continuously to weigh the cable tension in the pulling set of cables 42 and 49 so that undue cable strain may be continuously detected if the cable strain becomes too great, as when a heavy load of sediment is piled up on the blade elements, the slide rod 81 will rise until the arm 85 trips the reversing switch 84 and reverses the motor 27 so that the direction of movement of the frame 20 will be reversed in the basin, as will be described more Thus, the frame 20 may be automatically oscillated in short strokes to overcome a heavy sediment deposit which places a strain on the propelling set of cables, and this oscillation of the frame 20 will cause it to effectively and progressively push into the heavy sediment deposit until it becomes fluid enough to allow the frame progressively longer strokes and finally break up the deposit. The control units are effective to protect the cables against strains of any predetermined value, and the trip arm 85 on slide rod 81 may be adjustable to any position desired, or the reversing switch 84 may be adjustable on support 82 if desired, or both means may be adjustably mounted. if the trip arm 85 should be caused .to rise beyond switch 84 by unusual conditions, stop switch 83 will be actuated to stop the motor 27 and the action of the apparatus.

In certain cases, the sediment may be unevenly deposited so that the frame Ztl can ride over the heavy or thick zones without exceeding the predetermined cable strain and in this manner progressively reduce the same on successive passes along the basin floor 11.

Automatic reversal of movement of frame 20 at the ends of its full stroke along the basin floor 11 is provided for by utilizing one of the cables in conjunction with a pair of spaced reversing control switches. In the present embodiment of Figs. 1 and 2, cable 49 may be selected to carry a lug 92 which alternately trips reversing switches 93' and 94 positioned on suitable supports 95 and 96 respectively. These reversing switches 93 and 94 are located near opposite ends of basin It? in line with the cable 49, and are employed during normal full length reciprocation of the frame 20 in the basin when light loads of sediment are being moved.

Referring specifically to Fig. 2 it will be seen that a safety device is associated with each of the hangers 89 of the control units 37, 38, 39 and 40. Each of the safety devices includes a vertical rod 97 having its lower end 97a attached to the hanger 89 and a trip bar 98 carried by its upper end 9711. The safety rod 97 is slidably mounted adjacent to a normally closed safety shut-off switch 99 having contacts 9%. The safety rod 97 is vertically movable with the hanger 89 and weights 88, and the trip bar 98 is secured to the safety rod 97 in position to be out of contact with the switch 99 during normal operation of the apparatus. However, if a cable should break, the fall of the weight 88 would operate the safety rod 97 connected to the hanger 89 to open the contacts 99a of the switch 99. These switches 99 are connected to the motor 27 so that it will be stopped in the event any of the cables should break, as will become apparent hereinafter.

Referring to Figs. 4 and 5, a circular sedimentation basin 100 has a vertical wall 101 and a sloping floor 102 provided with a central circular gutter 103 communicating with a discharge conduit 104 for sediment. The gutter 103 surrounds a central upstanding column 105 which acts as a pivot for a sediment propelling and removing means. The latter means comprises combined carriage frame 106 and 106:: formed of suitable structural members in an open work assembly. A suitable bracing superstructure 107 (Fig. 5) is connected to the frames 106 and 1060. and the whole assembly extends diametrally across the basin in two directions at right angles with the radial portions of the frames 136 and 106a sloping upwardly to be substantially parallel with the floor 102 so as to sweep the floor area outwardly of the central gutter 103. The frames carry a plurality of rollers 108 engaging the central column to provide a pivot assembly, and similar rollers 109 carried by the superstructure 107 pivot about the column 135. Also the frames are provided with spaced sets of supporting rollers 110 engaging floor 102 so that the same may oscillate smoothly about the column 105. The radial portions of the frames carry a plurality of pivoted scraper elements, the elements 111 being set oppositely to the elements 112 in frame 106 and the elements 111a being set oppositely to elements 112a in frame 106a, and all of the scraper elements being effective to propel the sediment toward the central gutter 103 during oscillation. With the frames 1G6 and 106a moving in the direction of arrow C, the elements 111, 111a and 112 and 112a assume the full line positions, and reverse movement is accompanied by pivoting action of these scrappers into the dotted line positions. As between frames 106 and 106a, elements 111a are relatively off-set to elements 111, and elements 112a are otf-set to elements 112 so that the whole area of the basin floor 102 may be swept by all of the elements and no sediment be left unmoved thereby. Sediment being collected in the Central gutter 103 is moved toward the discharge conduit 104 by blades 113 carried at the central zone of the frames 106 and 106:: below the pivot rollers 168. Moreover, the superstructure 107 carries a bull wheel or pulley 114 by which the assembly may be oscillated about the pivot column 105.

Adjacent the basin wall 101, a pit 115 is provided and a platform 116 covers this pit except for slot-like openings 11'? therein. A pair of control units 118 and 119 are mounted over the platform openings 117. The units 118 and 119 are similar to the units 37 to 40 shown in Fig. l, and the parts thereof as described in connection with Figs. 1, 2 and 7 are designated by similar reference numerals. It is not believed necessary to repeat the description heretofore given in referring to units 118 and 119. Drive motor 12%) is belt connected to a speed reducer unit 121 and a shaft 122 carried in bearing stands 123 is connected to the unit 121 by a suitable coupling 124. Shaft 122 carries a pair of drums 125 and 126 to which the ends of cables 127 and 127a are connected for simultaneous but alternate winding and unwinding action. Drum 125 is filled with several layers of cables 127 and drum 126 is relatively empty of cable 127a since it is acting to wind up cable 127a as drum 125 pays out cable 127 in order to oscillate the frame 136 and 106a in the direction of arrow C.

The cable 127a from drum 126 passes through control unit 119 by being run over the pulleys 86 and under the slack take-up pulley 90 therein. From unit 119, cable 127a passes downwardly into basin Ill?) and about cornering pulley 133 to and substantially more than one turn about the pulley 114 to a connection at 123:: oscillating the frames. Cable 127 is connected to the bull wheel 114 a 128 and leads to a second cornering pulley 131,

thence upwardly and over pulleys 86 and under pulley 90 in control unit 118 to the drum 125. The function of control units 118 and 119 is similar to control unit 37 described in the preceding example, except that the control switches 33 and 34 are connected in circuit with the motor for stopping or reversing the latter, as the case may be. So long as switches 83 and 84 are unaffected, automatic reversing action of frame 106 at the ends of its travel is under the control of lug 132 on cable 127,

"in Figs. 1 and 3.

- 7 which lug .actuates the reversing limit switch 133, and lug 132a on cable 127a which actuates a reversing limit switch 134. Switch .133 is mounted on a leg '75 of control unit 118 and switch 134 is similarly mounted on a leg of unit 119, as shown in Fig. 4.

In Fig. 6, a rectangular sedimentation basin is diagrammatically shown with a central sediment collecting gutter 141 connected to a discharge pit 142 at one end thereof. The sediment may be moved to pit 142 by a drag cable device 143 similar to the device 65 described In this arrangement, a sediment removing frame 144 having bottom rollers 145 and end rollers 146 moves along one side of gutter 141 and a second .similar frame 144a having the same arrangement of bottom rollers 145 and end rollers 146 moves along the opposite side of the gutter 141. The action of each frame is to propel the sediment in the direction toward the central gutter 141 as will be presently described.

This arrangement may be modified by eliminating one portion of the basin 149 and one frame, as frame 144a, so that the sediment collecting gutter 141 may be located at one side of the modified basin. Other modifications will be suggested after the principles of this invention are more fully appreciated.

Since frames 144 and 144a are similar, a description of one will suffice for both, keeping in mind that frame 144a may be operated oppositely to frame 144 in respect of its sediment propelling action toward gutter 141. Frame 144, for example, consists in a suitable open frame work of structural members in which a plurality of pairs of pivoted scraper elements 147 are mounted in off-set relation so as to sweep the whole area of the basin floor. In either direction of movement of the frames 144 and 144a, the scraper elements 147 are angularly positioned relative to the gutter 141 so that sediment contacted by the elements 147 will be moved angularly across the floor of the basin 140 to the gutter 141. This frame is reciprocated upon its rollers 145 and 146 by a system of cables or chains now to be described.

A plurality of drums 148 to 153 inclusive are driven together by motor 154 through a suitable speed reducer unit 155 in a manner similar to that heretofore pointed out. Each drum is associated with a control unit of the type corresponding to those described in Figs. 1, 2 and 7.

These control units are indicated as a group at 156.

Winding drum 148 has its cable 157 extending through unit 156 and passing around cornering pulleys 158, 159, and 160 to a connection 161 on frame 144. Unwinding drum 149 paired with drum 148 has its cable 162 extending through control unit 156 and passing about cornering pulleys 163, 164, 165 and 166 to a connection 167 on frame 144 opposite the connection 161 for cable 157.

Winding drum 158 has its cable 168 extending through control unit 156 and passing about cornering pulleys 169 and 170 to a connection 171 near the center of frame 144. Unwinding drum 151, paired with drum 150, has its cable 172 extending through control unit 156 and passing about cornering pulleys 173 and 174 to a connection 175 on frame 144 opposite connection 171 for cable 168. Likewise, winding drum 153 has its cable 176 extending through control unit 156 and passing about cornering pulleys 177, 178 and 179 to a connection 180 at the end of frame 144. Unwinding drum 152, paired with drum 153, has its cable 181 extending through control unit 156 and passing about cornering pulleys 182, 183, 184 and 185 to a connection 186 on frame 144 opposite connection 180 for cable 176. Thus winding drums 148, 150 and 153 propel the frame 144 in the direction of arrow D V and scraper elements 147 assume the full line positions 8 near the ends of the basin and in line with the span of cables 162. The action of frame 144a may be in unison with frame 144 or it may be activated in an opposite sense, as desired.

Referring now to Fig. 8, it will be seen that the electrical circuit for operating the sedimentation basin cleaning apparatus includes power source or main leads 192, 193 and 194 for the three phase motor 27. The main leads 192, 193 and 194 are connected to a motor armature reversing switch 196 through a master switch 195. The reversing switch 196 includes a switch element 197 movable between contacts 197a and contacts 197]; to connect the main lead 192 to a lead 202 to one phase winding (not shown) of the motor 27. A second switch element 198 of the reversing switch 196 is movable between contacts 198a and contacts 19%. One of the contacts 19811 is connected to a lead 203 to a second phase winding (not shown) of the motor 27, and the other contact 198a is connected to the main lead 194. One of the contacts 198k is connected to the lead 203 to the second phase winding of the motor 27, and the other contact 198b is connected to the main lead 193. Accordingly, movement of the switch element 198 between the contacts 198a and 19812 reverses the connection of the second phase winding of the motor 27 between the main leads 193 and 194. Similarly, a third switch element 199 is provided with contacts 19911 for connecting the main lead 193 to a lead 204 to a third phase winding (not shown) of the motor 27, and contacts 19911 for connecting the lead 204 to the main lead 194. Therefore, when the switch elements 197, 198 and 199 are moved simultaneously between their respective sets of contacts, the connection of the main leads 193 and 194 to the second and third phase windings of the motor 27 are reversed and the direction of rotation of the motor 27 and belt 29 are reversed. As discussed hereinbefore, the reversal of the motor 27 is effective to reverse the rotation of the drums 33, 34, 35 and 36 so that the cables will be payed out from or wound thereon, and the direction of movement of the frame 20 in the basin 10 will be reversed.

The switch elements 197, 198 and 199 are connected to a reversing contactor 200 having right and left-hand solenoids 209 and 210 adapted to be alternately energized to move the contactor 200 and reverse the position of the switch elements with their respective sets of contacts. The solenoid 209 is connected in series with the reversing switch 94 by a lead 207 between main lead 193 and main ead 194. The solenoid 210 is connected in series with reversing switch 93 by a lead 208 between main lead 192 and main lead 193. Therefore, when the frame 20 is moved to the right in Fig. 1 and the switch 94 is contacted by the lug 92 on the cable 49, the solenoid 209 is energized and the contactor 200 is moved to the right in Fig. 8 so that the main leads 192, 193 and 194 will be connected to the motor winding leads as shown. The motor 27 is reversed and the frame 20 is moved to the left in Fig. 1.

When the lug 92 contacts the switch 93 and the solenoid 210 is energized, the contactor 200 moves the switch elements to the left in Fig. 8 thereby reversing the main leads to the motor windings. The contactor 200 is maintained in either leftward or rightward position by a toggle 201. When the cleaning apparatus is operating under a light load, full basin length reciprocation will continue as long as desired. However, as previously discussed, when the cleaning apparatus is operative on heavy sedi ment loads, the cable strain will be increased and the safety means or control units 37 to 40 will be effective to provide short stroke reciprocation of the frame 20.

Referring again to Fig. 8 it will be seen that a pair of the reversing switches 84 are connected in parallel with the reversing switches 94 and 93 for the solenoids 209 and 210, respectively. The cables 42 and 49 cooperate in moving the cleaning means to the right in the basin, and it is desired to prevent an overload on these cables.

Therefore, the switches 84 associated with the cables 42 and 49 are connected in the circuit of the solenoid 209 so that whenever either of the cables 42 or 49 become taut enough to raise the rod 81 into contact with the switch 84, the solenoid 209 will be energized and the direction of movement of the frame 20 is reversed in the basin. Similarly, the switches 84 associated with the cables 53 and 60 are connected in the circuit of the solenoid 210. Regardless of which direction the frame is moving in the basin, a load above a predetermined value will cause one of the reversing switches 84 to close to energize a solenoid and-reverse the direction of movement of the frame in the basin whereby the cables under load will be relieved and the other cables will be actuated into pulling condition.

The leads 202, 203 and 204 to the motor windings are provided with a circuit breaker arrangement 205 including a solenoid 206, the deenergization of which is etfective for stopping the motor 27. The solenoid 206 is connected in a lead 211 between leads 203 and 204, and all of the switches 83 and 99 are connected in series therewith. Accordingly, if the trip arm 85 of any of the control units for the cables should move above the switch 84 without reversing the motor 27, a switch 83 will be contacted and opened whereby the solenoid 206 will be deenergized and the motor 27 will stop. Similarly, if any of the cables should break, weight 83 will drop below a predetermined level and the safety rod 97 will carry the bar 98 into contact with the safety switch 99 so that the contacts 99a will be opened and the solenoid 206 will be deenergized. The electrical circuit for the other basins 100 and 140 operate in a similar manner as the circuit just described for the basin 10.

It should now be apparent that in each embodiment herein disclosed the control units associated with the cable drums which are functioning to wind up the cable act continuously to weigh the cable tension and prevent loads building up in the sediment cleaning frames or carriages beyond a predetermined value, and should such excessive loads occur, the control units act first to reverse the motion of the frames and second to stop the driving motor. In like manner, cable elongation beyond a safe point or cable breakage will result in stopping the driving motors.

What I claim is:

1. In sediment cleaning apparatus for sedimentation basins having a collecting gutter, a frame movable in said basin in reverse directions, pivoted scraper elements carried by said frame to swing into opposite sediment moving positions upon reverse movements of said frame, cable means connected to said frame to propel the latter in opposite directions, said cable means extending to a control station adjacent the basin, cable winding drums at the control station to which said cable means is connected, and reversible motor means driving said drums together, said drums alternately winding in cable and unwinding cable; the improvement of control units adjacent said drums, said cable means extending through said control units, and cable tension weighing means in said control units, each cable tension weighing means including yieldable means movable toward and from a position corresponding to a predetermined maximum cable tension value, a weighted device connected to said cable means to move in response to cable tension re action and move said yieldable means toward said predetermined position, said Weighted device also acting alternately to absorb slack in said cable means coming from the unwinding drum, and control means at said maximum tension position operable by said yieldable means to reverse said motor means.

2. In sediment cleaning apparatus for sedimentation basins having a collecting gutter, a frame movable in the basin in reverse directions, scrapers carried by said frame to propel the sediment toward the collecting gutter in both directions of frame movement, a cable system connected to said frame for reversely moving the frame, and motor driven drums connected to said cable system for alternately winding in and paying out cable to reverse frame movement; the improvement of control units operatively connected wtih said cable system to respond to tension loads in said cable system to absorb slack in said cable system, said control units including means connected to said motor driven drums to reverse the latter, weighted means riding on said cable system to move in response to tension and slack in the cable system, and yieldable means actuated by said weighted means in response to tension in said cable system to actuate said reversing means.

3. In sediment cleaning apparatus for sedimentation basins having a collecting gutter: the combination with a frame movable in opposite directions in the basin, scraper elements movably mounted in said frame to assume sediment propelling positions in accordance with the direction of frame movement in the basin, a cable system connected to said frame, cable drums, reversible motor means connected to said cable drums to rotate the latter together, said cable system being connected to said cable drums in opposite winding directions so that said cable system is simultaneously wound onto and payed out from said cable drums to effect reversal of frame movement in the basin, and means actuated by said cable system to reverse said motor means to limit the travel of said frame in its opposite directions of movement in the basin; of means responsive to tension in said cable system to additionally reverse said motor means and limit the tension therein to a predetermined value, said last means including weighted means riding on portions of said cable system to move in response to cable tension, reversing controls connected to said reversible motor means and spring means engaged by said weighted means to be compressed thereby and move in response to the weight of the tension loads in said cable system, said spring means acting to actuate said reversing controls to reverse said motor means upon tension loads exceeding a predetermined value.

4. In sediment cleaning apparatus for sedimentation basins having a collecting gutter, a frame movable in opposite directions in the basin; scraper elements movably mounted in said frame to assume alternate positions to propel sediment toward the gutter for opposite directions of frame movement, reversibly rotatable drums, and a cable system connected to said drums and to said frame and acting alternately upon reversals of drum rotation to wind up a portion of said cable system and to pay out another portion of said cable system; the improvement of control units for each portion of said cable system each including a weighted device riding upon and movable to take up slack in the portions of said cable system being payed out from said drums, yieldable means adapted to be engaged by said weighted device to continuously weigh the tension load in the portion of said cable system being wound up by said drums, said yieldable means being movable by said weighted device toward a position indicative of a predetermined tension load in said cable system, and means in said position operably connected to said reversible rotatable drums to be actuated by said yieldable means for effecting reversal of rotation of said drums.

5. In sediment cleaning apparatus for sedimentation basins having a collecting gutter, a frame reversibly movable in the basin, scraper elements pivoted in said frame to move into alternate positions upon reversals of frame movement to propel sediment to the gutter, reversibly rotatable drums, and a cable system connected to said drums and to said frame and acting alternately upon reversals of said drum rotation to wind up a portion of said cable system and to pay out another portion of said cable system; the improvement of control units for each portion of said cable system each including a Weighted device carried by said cable system, yieldable means References Cited in the file of this patent engageable by said Weighted device and movable in a UNITED STATES PATENTS direction to weigh the tension load in said cable system, 2 Dixon Oct 22 "1895 means actuated by said yieldable means upon a predeter- 1 Clark 1928 mined movement of the latter means in response to ex- 5 1932' cessive tension loads to reverse rotation of said drums, 5 4 I Wing Man 0 1934 other means actuatable to stop drum rotation upon break- 2 101 0 0 d D 7 1937 age of said cable system, and a member carried by said 2,295,391 Dn di Sept, 8, 1942 Weighted device to actuate said other means in response 10 2,670,080 Scott Feb. 23, 1954 to fall of said weighted device due to cable breakage. 2,681,184 Thomas June 15, 1954 

